CN114101818A

CN114101818A - Method for processing surface microtexture by maskless electrolysis

Info

Publication number: CN114101818A
Application number: CN202111472103.4A
Authority: CN
Inventors: 王荣贺; 郭亚鑫; 周云鹏; 张爱梅
Original assignee: Zhengzhou University
Current assignee: Zhengzhou University
Priority date: 2021-12-06
Filing date: 2021-12-06
Publication date: 2022-03-01

Abstract

The invention discloses a maskless electrolytic machining method for a surface microtexture, which is characterized in that a tool electrode in the maskless electrolytic machining method comprises a conductive layer, a non-conductive layer and a micro electrode, wherein an electrolyte dispersion channel is machined on the non-conductive layer. The method comprises the steps of coaxially mounting a tool electrode and a workpiece fixed on a tool clamp, and enabling a machining gap to be reserved between the tool electrode and the surface to be machined of the workpiece; connecting the conducting layer and the workpiece with the cathode and the anode of an electrolytic power supply respectively; injecting electrolyte and shunting to the processing gap through the dispersion channel; and (3) switching on an electrolytic power supply, and selectively corroding the surface to be processed of the workpiece under the combined action of the electrolyte and the electric field to obtain the surface microtexture. The invention does not need the complex process of mask preparation, can process any complex curved surface, and the tool electrode can be reused, the process is simple, and the cost is low.

Description

Method for processing surface microtexture by maskless electrolysis

Technical Field

The invention relates to the field of precision and special processing, in particular to a maskless electrolytic processing method of a metal surface microtexture.

Background

In recent years, the application of micro-nano surface microtexture in the aspects of friction reduction and drag reduction is widely researched. The surface microtexture is that a microstructure array of pits, bulges or grooves and the like with a certain size and arranged regularly is processed on the surface of a workpiece, so that the performance of the surface of the workpiece is changed, and the surface microtexture has good application prospects in the aspects of antifriction lubrication, biomedicine, super-hydrophobic surfaces and the like.

The current processing methods of the surface microtexture mainly comprise laser processing, mechanical processing, abrasive gas jet processing, electric spark processing, electrolytic processing and the like. Electrolytic machining is the mainstream research method by virtue of the advantages of high machining efficiency, no tool electrode loss, wide forming range, batch machining and the like. The mask electrolytic processing technique generally includes steps of coating a photoresist on the surface of a workpiece or pasting a photosensitive blue film on the surface of the workpiece, and then performing exposure, development and the like, so that a template with a certain pattern is formed on the surface of the workpiece, and thus, the exposed part is dissolved in the electrolytic processing process to form a surface microtexture. But the steps of gluing or film pasting, exposure, development, glue removal and the like are required in the mask preparation process, the process is complex, the repeated use cannot be realized, the price of an exposure machine is high, the requirement on production strips is high, and the comprehensive cost is too high.

The invention patent CN 108274083A discloses a method for electrolytic machining of surface microtexture, which uses a photoconductive layer and a transparent conductive layer to form a cathode, irradiates the photoconductive layer with laser to form a conductive template with a certain pattern, and dissolves the part of the workpiece surface corresponding to the conductive template, thereby realizing the electrolytic machining of the surface microtexture. However, the surface microtexture profile in this method is formed by laser irradiation, which is real-time, and cannot be formed at one time, the processing efficiency is greatly reduced, and the processing accuracy is unstable due to the influence of the electrolyte and the lens mounting accuracy during the propagation of the laser beam.

Therefore, the existing mask electrolytic machining method and the existing machining method for the tool electrode made of the photoconductive material have certain limitations and have certain difficulties in practical production. Therefore, the invention aims to provide a tool electrode which can be repeatedly used and is not limited by a mask, and can be processed into various complex surfaces corresponding to the surfaces to be processed, so that the production efficiency is improved, and the production cost is reduced.

Disclosure of Invention

In accordance with the above problems, a method for maskless electrochemical machining of a microtexture of a surface is provided. The invention adopts the technology of the cathode electrode of the tool integrating the electrode and the mask, the tool electrode can be repeatedly used, the electrode has no loss, the complex process of gluing, exposing and developing in the repeated preparation of the mask is avoided, and the stability of the processing quality and the processing efficiency are improved.

The technical scheme of the invention is as follows:

s1, fixing a workpiece on a tool fixture, and coaxially installing a tool electrode and the workpiece to ensure that a machining gap is reserved between the tool electrode and the surface to be machined of the workpiece, and the tool electrode is tightly pressed on the workpiece from top to bottom to ensure certain tightness;

s2, connecting the positive electrode and the negative electrode of the electrolytic power supply with the conducting layers of the workpiece and the tool electrode respectively;

s3, starting the electrolyte to enter the electrolyte dispersion channel through the electrolyte injection hole, so that the electrolyte uniformly enters the machining gap after passing through the shunting action of the dispersion channel;

and S4, starting an electrolytic power supply to electrify the tool electrode and the workpiece, and carrying out anodic dissolution on the area corresponding to the micro electrode on the surface to be processed under the combined action of the electrolyte and the electric field so as to form an array with a certain micro-morphology on the surface to be processed of the workpiece, namely, the surface micro-texture is prepared.

The tool electrode is a mask and electrode integrated tool electrode which is composed of a conductive layer, a non-conductive layer and a micro electrode, wherein the micro electrode is regularly arranged in the non-conductive layer.

The micro electrode can be made into various shapes according to the appearance of the surface micro texture, and the material of the micro electrode is a conductive metal material which does not react with the electrolyte.

The tool electrode comprises an electrolyte dispersing channel, and electrolyte entering from an electrolyte injection hole enters a machining gap after being shunted by the electrolyte dispersing channel.

Compared with the prior art, the invention has the following outstanding advantages:

1. the invention arranges the micro electrode in the non-conductive layer to play a role of side insulation, which is beneficial to improving the localization of the micro texture on the surface of the electrolytic machining; compared with the traditional method for electrolytically processing the surface microtexture of the mask, the method does not need the processes of gluing/film pasting, exposure, development and the like, simplifies the processing process, improves the processing efficiency, reduces the production cost, and solves the problem of insecure mask pasting; and the size of a machining gap can be increased without using a mask, so that the electrolyte flows more sufficiently, products and heat generated by machining are taken away in time, and the machining precision is improved.

2. The invention increases the electrolyte dispersion channel, can ensure that the electrolyte uniformly enters the processing gap in the circumferential direction, and can ensure the consistency and uniformity of the surface microtexture.

3. According to the method provided by the invention, the tool electrode can be processed into a complex shape corresponding to the tool electrode according to the substitute processing surface, such as an irregular curved surface.

Drawings

FIG. 1 is a schematic diagram of a maskless electrochemical machining system for microtexturing a surface.

FIG. 2 is an axial two-dimensional cross-sectional view of the present invention for preparing a surface microtexture on the inner surface of a cylindrical workpiece.

FIG. 3 is a radial two-dimensional cross-sectional view of the present invention for preparing a surface microtexture on the inner surface of a cylindrical workpiece.

In the figure: 1. the method comprises the following steps of injecting electrolyte into a hole, 2, a workpiece, 3, a non-conductive layer, 4, a conductive layer, 5, a machining gap, 6, a micro electrode, 7, an electrolyte dispersing channel, 8, an electrolysis power supply and 9, electrolyte.

Detailed Description

The technical solutions in the embodiments of the present invention will be described in detail and fully with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments.

(1) Before the experiment, a tool electrode is manufactured according to the appearance and the distribution rule of the microtexture on the surface of the workpiece, firstly, a micro electrode 6 is arranged on a non-conductive layer 3 according to the distribution rule of the microtexture on the surface, and the non-conductive layer 3 is processed into a shape corresponding to the surface to be processed of the workpiece 2 by a mechanical processing method for standby;

(2) before the experiment, an electrolyte injection hole 1, a pressure circulating pump, a filter and an electrolytic tank are connected in sequence by a hose to form a complete electrolyte circulating system;

(3) cleaning a cast iron cylindrical workpiece 2 with the inner diameter of 140mm, the wall thickness of 6mm and the height of 270mm by ultrasonic waves for three minutes to remove oil stains, cleaning the workpiece by absolute ethyl alcohol, and finally drying the workpiece; mounting the processed workpiece 2 on a positioning fixture, selecting a tool electrode matched with the workpiece to be inserted into the workpiece, adjusting the position of the tool electrode and the workpiece to be processed to ensure that the tool electrode and the workpiece to be processed are coaxial and ensure that the processing gap between the tool electrode and the surface to be processed of the workpiece is uniformly distributed, and keeping the upper surface of the workpiece in close contact with the tool electrode to prevent electrolyte from overflowing;

(4) respectively connecting the positive electrode and the negative electrode of an electrolysis power supply 8 to the workpiece 2 and the conductive layer 4, and adjusting the voltage of the electrolysis power supply 8 to 10V and the duty ratio to 0.25;

(5) starting a pressure circulating pump in an environment of 25 ℃, and adding NaNO with the mass fraction of 10%₃The electrolyte 9 is injected into the electrolyte dispersion channel 7 from the electrolyte injection hole 1 at a certain pressure and then is distributed to the machining gap 5, so that the machining gap 5 is fully filled with the electrolyte;

(6) after the machining gap 5 is filled with the electrolyte 9, the electrolytic power supply 8 is started, and at this time, the machining-substitute surface of the workpiece is selectively corroded under the combined action of the electric field and the electrolyte, as shown in the process of fig. 2, to form micro pits with a shape similar to the array micro pits, a diameter of 500 μm, and a depth of 100 μm. When the machining size requirement is met, the electrolysis power supply 8 is disconnected, and then the liquid supply is stopped. The depth can be controlled by adjusting the processing time, the shape and the size of the electrode are related to a micro electrode, and a corresponding tool electrode can be prepared according to the appearance of the surface micro texture;

(7) and taking down the processed workpiece, ultrasonically cleaning for two minutes, drying, and removing the electrolyte on the surface of the workpiece to prevent the workpiece from being corroded.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. A method for processing surface microtexture by maskless electrolysis comprises the following steps:

s1, fixing a workpiece on a tool fixture, coaxially installing a tool electrode and the workpiece (2), and tightly contacting and keeping sealing the upper surface of the workpiece (2) and the tool electrode;

s2, connecting the anode of an electrolytic power supply (8) with the workpiece (2), and connecting the cathode with the conducting layer (4) of the tool electrode;

s3, starting the electrolyte to enter the electrolyte dispersion channel (7) through the electrolyte injection hole (1) and flow into the electrolytic cell through the machining gap (5);

and S4, starting an electrolytic power supply (8) to electrify the micro electrode (6) in the tool electrode and the workpiece (2) to form an electric field, wherein the surface to be machined of the workpiece (2) is selectively corroded under the combined action of the electric field and electrolyte, and an array with a certain micro-morphology is formed on the surface to be machined of the workpiece, so that the surface micro-texture is prepared.

2. The method according to claim 1, characterized in that the tool electrode consists of a conductive layer (4), a non-conductive layer (3) and microelectrodes (6), the microelectrodes (6) being regularly arranged in the non-conductive layer (3) and being connected to the conductive layer (4).

3. The method according to claim 1, characterized in that the micro-electrodes (6) have a cross-section of circular, triangular, rectangular shape and are made of a material selected from the group of conductive metals that do not react with the electrolyte (9).

4. A method according to claim 2, characterized in that the conductive layer (4) is a layer of conductive metal material with a thickness of 0.5-1mm plated on the non-conductive layer (3) and connected to an array of micro-electrodes.

5. A method according to claim 1, characterized in that the tool electrode comprises an electrolyte dispersion channel (7), the upper side of the electrolyte dispersion channel (7) being connected to the electrolyte injection hole (1) and the lower side being in communication with the machining gap (5).